[maria-rcks]

Part 6 of 6 of the T3 Code redesign. Chats, files, terminals and the browser open as panes in a workspace instead of fixed side panels.

• workspace panes with tab strips: reorder by drag, overflow scrolling that reveals the active tab, restoring closed tabs, and terminal panes in tab drop targets.
• layout hints and a guided tour introduce the workspace and stay inside the viewport on mobile.
• ⌥⌘ + scroll moves between columns. Pane backgrounds paint without a retained compositor layer, and hints follow compositor motion without a continuous repaint.
• the usage page reuses the floating settings shell.

The niri parts are behind Settings > Labs > Scrolling workspaces, off by default: the sideways scrolling strip and swipes, extra workspaces and the overview, and the layout tour and hints. With it off, panes shrink to fit; splits, tabs, side panes and per-project layout templates stay on for everyone. cmd+N and cmd+shift+O open main's project picker when there are several projects, and new threads replace the focused tab instead of opening a new one.

Needs approval: Theo for vite.config.ts (lint ceilings only); Theo or Julius for packages/contracts (ipc, keybindings, server, settings, including the new scrollingWorkspacesEnabled client setting, which decodes to false).

Stack

Do not merge: this stack still needs review. Each PR targets the one below it.

1. feat(web): establish redesign primitives and shell #28839 1-primitives-shell
2. feat(web): redesign composer and conversation timeline #28840 2-composer-timeline
3. feat(web): redesign review panels and supporting pages #28841 3-panels-pages
4. feat(web): redesign settings and setup surfaces #28842 4-settings-setup
5. feat(web): style dictation with the redesign primitives #28844 5-voice
6. feat(web): add workspace panes and transitions #28845 6-workspace-panes (this PR)

Evidence

Captured against base 5ba6597504b681819ff657e5e0808c54b37edb42 and head f6f00d4f4fe175e66f5d7fc6018ace6a1c841ca3, using separate seeded worktrees and the same replay scenarios at 1280 × 720. Dark mode unless labeled light. No code, PR, or branch changes.

Chat, terminal, and the same server/package.json file: the fixed right panel becomes an independent workspace column.

Browser: the same example.com page remains usable beside the chat and terminal, with the file and browser represented as workspace tabs.

Workspace tab strip: overflow scrolling and active filename reveal were exercised with package.json, README.md, tsconfig.json, vite.config.ts, and the browser. Measured 466 px of tab content in a 326 px viewport; selecting vite.config.ts revealed its filename. Native drag reordered vite.config.ts before README.md and before tsconfig.json in separate passes. The base has no workspace pane tab strip; its fixed panel baseline is shown above.

Restore a closed chat: Ctrl+Shift+T reopened Replay: todo-list with its existing conversation. Closing and restoring a browser also retained its URL and page. Chat-tab restore has no equivalent on the base.

Layout introduction and guided tour are new on this layer. Opened Show me, advanced through all five steps, entered the overview lesson, and finished back in the workspace.

Usage adopts the floating settings shell. Both refs show the same real provider error, with matching selections, in dark mode.

Usage, matching light-mode pair.

Nine-second recording: native tab drag, horizontal column scrolling, closing the chat, and restoring it. Reviewed the exported sequence, then played the uploaded video to completion and checked seeking.

Findings and limits:

• The recording shows a brief empty pane during chat restoration around 5–6 seconds, before its conversation returns. This is observed app behavior, not a successful no-blank-frame result.
• Usage retrieval is unverified: both refs report Codex could not read usage (JSON-RPC -32600). No usage data was fabricated.
• This is a Linux web browser. Ctrl+Alt plus horizontal scroll moved the workspace strip from 223 px to 0 px. The macOS ⌥⌘ path, Electron desktop, native mobile, and three-finger gestures remain unverified.
• Browser automation intermittently disconnected. Native drag succeeded after targeting the visible pane specifically; exploratory pointer-event checks were not used in the final recording.
• No automated test suite or production-build checks were run for this evidence-only task.

Verification

Every layer, rebased on main 9469095, passes typecheck, knip, lint and format on Blacksmith on its own. At layer 6, the web suite passes (unit and browser). The desktop suite fails one libsecret test, which fails the same way on main. GitHub CI runs the full suite on every layer.

Done with Claude Code (Opus 5.5) and Codex (gpt-6.1-sol high) children in T3 Code.

🤖 Generated with Claude Code

[macroscopeapp]

Macroscope skipped reviewing this pull request. Per-review cost limit exceeded (workspace setting).

This review would cost an estimated $37.18, which exceeds your per-review limit of $15.00.

The top 3 files driving up this estimate:

File	Diff Size	Estimate
apps/web/src/layout/SurfaceHost.tsx	88.47KB	$3.31
apps/web/src/layout/layoutModel.ts	80.37KB	$3.01
apps/web/src/layout/Overview.tsx	55.80KB	$2.09

Tip

To get this pull request reviewed, you can:

1. Comment @macroscope-app on this PR to request a manual review (monthly spend limits still apply).
2. Exclude the file(s) above from review by adding a pattern to your .macroscope/ignore.md — note that creating this file replaces Macroscope's built-in default ignores rather than extending them.
3. Raise your cost limit in your workspace billing settings.

^{Turn off this reminder going forward}

[macroscopeapp]

Approvability

Verdict: Needs Human Approval

Macroscope's review found this PR requires human approval — This adds workspace panes and transitions and changes the default panel animation duration from 0 to 150 ms. The changed default experience requires human confirmation.

Needs human approval because:

• Per-review cost limit exceeded (workspace setting). Approvability relies on correctness review in order to determine eligibility

^{Review your spending limits in Billing settings, or comment @macroscope-app review this PR to bypass the limit and review now. You can add or adjust custom eligibility rules. Learn more.}

[github-actions]

Thread transfer impact

✅ Thread transfer remains within every enforced ceiling.

ℹ️ No successful main baseline artifact is available yet. This run establishes the initial measurement.

Provider	Metric	Main baseline	This PR	Impact	PR ceiling
Codex	Total thread wire	—	5.0 KiB	—	6.8 KiB	✅
Codex	Thread snapshot wire	—	3.8 KiB	—	4.9 KiB	✅
Codex	Live turn WebSocket wire	—	1.2 KiB	—	2.0 KiB	✅
Codex	Live turn WebSocket decoded	—	21.5 KiB	—	24.4 KiB	✅
Codex	Live turn messages	—	1	—	8	✅
Claude	Total thread wire	—	5.0 KiB	—	6.8 KiB	✅
Claude	Thread snapshot wire	—	3.8 KiB	—	4.9 KiB	✅
Claude	Live turn WebSocket wire	—	1.2 KiB	—	2.0 KiB	✅
Claude	Live turn WebSocket decoded	—	21.9 KiB	—	24.4 KiB	✅
Claude	Live turn messages	—	1	—	8	✅

Other scenarios

No main baseline exists yet for these 64 scenario measurements.

All 64 scenario measurements

Provider	Scenario	Metric	Main baseline	This PR	Impact	PR ceiling
Codex	short turn resume	WebSocket decoded	—	10.5 KiB	—	12.7 KiB	✅
Codex	short turn resume	WebSocket messages	—	2	—	2	✅
Codex	long turn running, cold open	HTTP decoded	—	281.7 KiB	—	302.7 KiB	✅
Codex	long turn running, cold open	rows	—	75	—	75	✅
Codex	long turn running, history page	HTTP decoded	—	92.4 KiB	—	107.4 KiB	✅
Codex	long turn running, history page	rows	—	75	—	75	✅
Codex	long turn finished, cold open	HTTP decoded	—	381.5 KiB	—	410.2 KiB	✅
Codex	long turn finished, cold open	rows	—	151	—	151	✅
Codex	long turn finished, socket cold open	WebSocket decoded	—	381.6 KiB	—	410.2 KiB	✅
Codex	long turn finished, socket cold open	WebSocket messages	—	2	—	2	✅
Codex	long turn finished, socket cold open	rows	—	151	—	151	✅
Codex	long turn finished, work page	HTTP decoded	—	186.2 KiB	—	200.2 KiB	✅
Codex	long turn finished, work page	rows	—	150	—	150	✅
Codex	idle thread resume	WebSocket decoded	—	65 B	—	200 B	✅
Codex	idle thread resume	WebSocket messages	—	1	—	1	✅
Codex	fleet shell snapshot	HTTP decoded	—	41.6 KiB	—	53.7 KiB	✅
Codex	fleet shell snapshot	rows	—	27	—	27	✅
Codex	fleet shell subscribe	WebSocket decoded	—	65 B	—	200 B	✅
Codex	fleet shell subscribe	WebSocket messages	—	1	—	1	✅
Codex	fleet shell resume check	HTTP decoded	—	18 B	—	100 B	✅
Codex	fleet shell resume check	rows	—	0	—	0	✅
Codex	stale shell reload	HTTP decoded	—	41.6 KiB	—	53.7 KiB	✅
Codex	stale shell reload	rows	—	27	—	27	✅
Codex	stale shell resume	WebSocket decoded	—	140 B	—	400 B	✅
Codex	stale shell resume	WebSocket messages	—	2	—	2	✅
Codex	stale todo list cold open	HTTP decoded	—	72.4 KiB	—	83.0 KiB	✅
Codex	stale todo list cold open	rows	—	75	—	75	✅
Codex	stale todo list cold open	nodes	—	2	—	4	✅
Codex	stale todo list cold open	subagents	—	2	—	4	✅
Codex	stale todo list cold open	plans	—	1	—	2	✅
Codex	stale todo list cold open	providerTurns	—	1	—	2	✅
Codex	stale todo list cold open	checkpoints	—	1	—	2	✅
Claude	short turn resume	WebSocket decoded	—	10.6 KiB	—	12.7 KiB	✅
Claude	short turn resume	WebSocket messages	—	2	—	2	✅
Claude	long turn running, cold open	HTTP decoded	—	283.3 KiB	—	302.7 KiB	✅
Claude	long turn running, cold open	rows	—	75	—	75	✅
Claude	long turn running, history page	HTTP decoded	—	93.4 KiB	—	107.4 KiB	✅
Claude	long turn running, history page	rows	—	75	—	75	✅
Claude	long turn finished, cold open	HTTP decoded	—	384.2 KiB	—	410.2 KiB	✅
Claude	long turn finished, cold open	rows	—	151	—	151	✅
Claude	long turn finished, socket cold open	WebSocket decoded	—	384.3 KiB	—	410.2 KiB	✅
Claude	long turn finished, socket cold open	WebSocket messages	—	2	—	2	✅
Claude	long turn finished, socket cold open	rows	—	151	—	151	✅
Claude	long turn finished, work page	HTTP decoded	—	188.1 KiB	—	200.2 KiB	✅
Claude	long turn finished, work page	rows	—	150	—	150	✅
Claude	idle thread resume	WebSocket decoded	—	66 B	—	200 B	✅
Claude	idle thread resume	WebSocket messages	—	1	—	1	✅
Claude	fleet shell snapshot	HTTP decoded	—	42.2 KiB	—	53.7 KiB	✅
Claude	fleet shell snapshot	rows	—	27	—	27	✅
Claude	fleet shell subscribe	WebSocket decoded	—	66 B	—	200 B	✅
Claude	fleet shell subscribe	WebSocket messages	—	1	—	1	✅
Claude	fleet shell resume check	HTTP decoded	—	18 B	—	100 B	✅
Claude	fleet shell resume check	rows	—	0	—	0	✅
Claude	stale shell reload	HTTP decoded	—	42.2 KiB	—	53.7 KiB	✅
Claude	stale shell reload	rows	—	27	—	27	✅
Claude	stale shell resume	WebSocket decoded	—	140 B	—	400 B	✅
Claude	stale shell resume	WebSocket messages	—	2	—	2	✅
Claude	stale todo list cold open	HTTP decoded	—	73.4 KiB	—	83.0 KiB	✅
Claude	stale todo list cold open	rows	—	75	—	75	✅
Claude	stale todo list cold open	nodes	—	2	—	4	✅
Claude	stale todo list cold open	subagents	—	2	—	4	✅
Claude	stale todo list cold open	plans	—	1	—	2	✅
Claude	stale todo list cold open	providerTurns	—	1	—	2	✅
Claude	stale todo list cold open	checkpoints	—	1	—	2	✅

Baseline: unavailable · PR result: fb2762f · Source CI: success

Scenario and decoded snapshot size

10 historical turns, 5 command tools per turn, 878.9 KiB retained MCP result per historical turn, and a 1.05 MiB retained result in the measured turn.

• Codex decoded thread snapshot: 108.5 KiB
• Claude decoded thread snapshot: 108.8 KiB

Updated in place by a trusted workflow. PR artifacts are strictly validated and never executed.

[coderabbitai]

Finishing Touches

Generate unit tests (beta)

• Commit to this branch
• Create a new PR

• Autofix · Keep fixing CodeRabbit findings and required CI, and resolving merge conflicts